磁场定向等离子体流中剪切引起的流体动力学不稳定性的离子温度梯度敏感性
Ion-temperature-gradient sensitivity of the hydrodynamic instability caused by shear in the magnetic-field-aligned plasma flow
摘要：
交叉磁场（即，对于空间和实验室等离子体来说，离子温度的垂直（垂直）分布和磁场对准（平行）等离子体流的垂直分布有时是不均匀的。在文献中已经广泛讨论了由离子温度分布中的梯度或由平行流中的剪切引起的不稳定性。在本文中，流体动力学等离子体的稳定性进行了研究，实和虚频率的范围内的剪切参数，归一化波数，密度梯度和离子温度梯度尺度长度的比例进行了量化，并说明了反朗道阻尼的作用的情况下，离子温度梯度和平行流剪切。我们发现，增加离子温度梯度降低了流体动力学平行流剪切不稳定性，也被称为平行开尔文-亥姆霍兹不稳定性或D 'Angelo不稳定性的不稳定阈值。我们还发现，动力学不稳定性产生的耦合，加强行动的自由能源。对于可比的电子和离子的温度的情况下，我们分析说明的D 'Angelo不稳定性的动力学不稳定性的剪切参数，归一化的波数，和密度梯度和离子温度梯度尺度长度的比例是不同的，我们属性的变化，在稳定性的变化量的逆离子朗道阻尼的变化。我们发现，附近的归一化波数$k_{\perp} ρ_{i}$的顺序统一，频率的实部和虚部值变得可比和增长率最大化。
英文摘要：
The cross-magnetic-field (i.e., perpendicular) profile of ion temperature and the perpendicular profile of the magnetic-field-aligned (parallel) plasma flow are sometimes inhomogeneous for space and laboratory plasma. Instability caused by a gradient in either the ion-temperature profile or by shear in the parallel flow has been discussed extensively in the literature. In this paper, hydrodynamic plasma stability is investigated, real and imaginary frequency are quantified over a range of the shear parameter, the normalized wavenumber, and the ratio of density-gradient and ion-temperature-gradient scale lengths, and the role of inverse Landau damping is illustrated for the case of combined ion-temperature gradient and parallel-flow shear. We find that increasing the ion-temperature gradient reduces the instability threshold for the hydrodynamic parallel-flow shear instability, also known as the parallel Kelvin-Helmholtz instability or the D'Angelo instability. We also find that a kinetic instability arises from the coupled, reinforcing action of both free-energy sources. For the case of comparable electron and ion temperature, we illustrate analytically the transition of the D'Angelo instability to the kinetic instability as the shear parameter, the normalized wavenumber, and the ratio of density-gradient and ion-temperature-gradient scale lengths are varied and we attribute the changes in stability to changes in the amount of inverse ion Landau damping. We show that, near a normalized wavenumber $k_{\perp} ρ_{i}$ of order unity, the real and imaginary values of frequency become comparable and the growth rate maximizes.
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